1. Field of the Invention
The present invention relates to a lens-exchangeable camera and in particular to a lens-exchangeable camera in which a communication start signal is sent from the body side to the lens side.
2. Description of the Related Art
A camera system has been proposed in which a lens is mounted with a microcomputer and a microcomputer on the body side communicates with the microcomputer of the lens side to control the operation of the camera. Such a camera includes a camera in which the lens side has the initiative in various communications between the body and the lens (referred to as BL communications hereinafter) and a camera in which the body side has the initiative in BL communications.
Generally, no battery is incorporated within the lens. When the lens is mounted on the body, the microcomputer on the lens side receives power supply from the body side and starts to operate. In starting to operate, the microcomputer on the lens side requires some time after the power supply, since it waits for stabilization in signaling the signaling side, prepares for communication with the body or the like.
A camera which performs a conventional BL communication is configured as described above. In the camera system in which the lens side has the initiative in BL communication, communication with the body can be started as soon as the time described above elapses. In the camera system in which the body side has the initiative in the communication, however, preparation for communication on the lens side must be completed first and communication is then started. However, since the time described above varies depending on the performance of the microcomputer for the lens side, the temperature of the environment and the like, the microcomputer on the body side need start communication depending on the lens of a plurality of lenses used in combination which consumes the longest preparation time, and thus it takes a long time until communication is started.